A common semiconductor device has protruding electrodes on a principal surface (rear face) to be mounted on a circuit board. The protruding electrodes are formed, for example, by solder balls or bumps.
In mounting the semiconductor device on the electrodes of the circuit board, a film-type underfill material is joined to a wafer. The film-type underfill material is used as a sheet for joining the semiconductor device to a mount position of the circuit board. Thereafter, each diced semiconductor element is placed on the film-type underfill material and is pressed, thereby being mounted on the circuit board. See Japanese Patent Publication No. 2002-231765A and Japanese Patent No. 4438973.